3 * @purpose Implementation of dilatometer related functions
8 #include "dilatometer.h"
12 static double test_left, test_right;
14 // Canny Edge algorithm variables
16 int lowThreshold = 30;
20 /** Buffers for storing image data. **/
21 static CvMat * g_srcRGB = NULL; // Source Image
22 static CvMat * g_srcGray = NULL; // Gray scale of source image
23 static CvMat * g_edges = NULL; // Detected Edges
25 /** Pointers for capturing image **/
26 static CvCapture * g_capture = NULL;
27 static IplImage * frame = NULL; // This is required as you can not use capture with CvMat in C
31 * Create a test image using left as left edge and right as right edge positions
33 void Dilatometer_TestImage()
36 g_srcRGB = cvCreateMat(480, 640, CV_8UC3);
38 for( int x = 0; x < 640; ++x)
40 for (int y = 0; y < 480; ++y)
43 for( int i = 0; i < 3; ++i)
45 s.val[i] = 210 + (rand() % 1000) * 1e-0 - (rand() % 1000) * 1e-0;
46 // Produce an exponential decay around left edge
48 s.val[i] *= exp( (x - test_left) / 25);
50 s.val[i] *= exp( (test_left - x) / 25);
51 // Produce an exponential decay around right edge
52 else if( x < test_right)
53 s.val[i] *= exp( (x - test_right) / 25);
55 s.val[i] *= exp( (test_right - x) / 25);
57 cvSet2D(g_srcRGB,y,x,s);
61 if (g_srcGray == NULL)
63 g_srcGray = cvCreateMat(g_srcRGB->rows,g_srcRGB->cols,CV_8UC1);
65 cvCvtColor(g_srcRGB,g_srcGray,CV_RGB2GRAY);
69 * Cleanup Dilatometer pointers
71 void Dilatometer_Cleanup()
73 if (g_capture != NULL)
74 cvReleaseCapture(&g_capture);
76 cvReleaseMat(&g_srcRGB);
77 if (g_srcGray != NULL)
78 cvReleaseMat(&g_srcGray);
80 cvReleaseMat(&g_edges);
82 cvReleaseImageHeader(&frame);
86 * Get an image from the Dilatometer
88 static bool Dilatometer_GetImage()
91 // If more than one camera is connected, then input needs to be determined, however the camera ID may change after being unplugged
92 g_capture = cvCreateCameraCapture(0);
93 //If cvCreateCameraCapture returns NULL there is an error with the camera
94 if( g_capture == NULL)
97 // Get the frame and convert it to CvMat
98 frame = cvQueryFrame(g_capture);
100 g_srcRGB = cvGetMat(frame,&stub,0,0);
102 if( g_srcRGB == NULL)
105 // Convert the image to grayscale
106 if (g_srcGray == NULL)
108 g_srcGray = cvCreateMat(g_srcRGB->rows,g_srcRGB->cols,CV_8UC1);
111 cvCvtColor(g_srcRGB,g_srcGray,CV_RGB2GRAY);
116 void CannyThreshold()
118 if ( g_edges == NULL)
120 g_edges = cvCreateMat(g_srcGray->rows,g_srcGray->cols,CV_8UC1);
123 // Commented out lines are used during testing to show the image to screen, can also save the test images
124 //cvShowImage("display", g_srcGray);
127 // Reduce noise with a kernel blurxblur. Input the grayscale source image, output to edges. (0's mean it's determined from kernel sizes)
128 cvSmooth( g_srcGray, g_edges, CV_GAUSSIAN, blur, blur ,0 ,0 );
131 //cvSaveImage("test_blurred.jpg",g_edges,0);
132 printf("what about here?\n");
134 cvShowImage("display", g_edges);
136 // Find the edges in the image
137 cvCanny( g_edges, g_edges, lowThreshold, lowThreshold*ratio, kernel_size );
140 //cvSaveImage("test_edge.jpg",g_edges,0);
142 cvShowImage("display", g_edges);
149 * Read the dilatometer image. The value changed will correspond to the new location of the edge.
150 * @param val - Will store the read value if successful
151 * @param samples - Number of rows to scan (increasing will slow down performance!)
152 * @returns true on successful read
154 bool Dilatometer_GetEdge( double * value, int samples)
158 // Get the image from the camera
159 result = Dilatometer_GetImage();
160 // If an error occured when capturing image then return
164 // Apply the Canny Edge theorem to the image
167 int width = g_edges->cols;
168 int height = g_edges->rows;
170 // If the number of samples is greater than the image height, sample every row
171 if( samples > height)
177 int num_edges = 0; // Number of edges. if each sample location has an edge, then num_edges = samples
179 for (int i=0; i<samples; i++)
181 // Determine the position in the rows to find the edges.
182 // This will give you a number of evenly spaced samples
183 sample_height = ceil(height * (i + 1) / samples) -1;
185 // Need to go through each pixel of a row and find all the locations of a line. If there is more than one pixel, average it. note this only works if the canny edge algorithm returns lines about the actual line (no outliers).
189 for ( int col = 0; col < width; col++)
191 // Count the number of points
192 // Get the threshold of the pixel at the current location
193 CvScalar value = cvGet2D(g_edges, sample_height, col);
194 if( value.val[0]> THRES)
196 edge_location += col;
202 average += ( edge_location / num );
207 average /= num_edges;
211 result = true; //Successfully found an edge
218 * Read the dilatometer image. The value changed will correspond to the new location of the edge.
219 * @param val - Will store the read value if successful
220 * @returns true on successful read
222 bool Dilatometer_Read( double * value)
224 bool result = Dilatometer_GetEdge(value, SAMPLES);
229 * Initialise the dilatometer
231 void Dilatometer_Init()
233 // Make an initial reading (will allocate memory the first time only).
235 Dilatometer_GetEdge(&val, 1);
238 // Overlays a line over the given edge position
239 void Draw_Edge(double edge)
243 for( int i = 0; i < g_srcGray->rows; i++)
245 cvSet2D(g_edges,i,edge,value);
247 cvShowImage("display", g_edges);
249 //cvSaveImage("test_edge_avg.jpg",g_edges,0);
253 static void Dilatometer_GetImageTest( )
255 //Generates Test image
256 //Dilatometer_TestImage();
259 g_srcGray = cvLoadImageM ("testimage4.jpg",CV_LOAD_IMAGE_GRAYSCALE );
263 * For testing purposes
265 int main(int argc, char ** argv)
267 //cvNamedWindow( "display", CV_WINDOW_AUTOSIZE );// Create a window for display.
268 //gettimeofday(&start, NULL);
273 cvNamedWindow( "display", CV_WINDOW_AUTOSIZE);
277 Dilatometer_GetEdge(&edge,20000);
278 //For testing purposes, overlay the given average line over the image
281 cvDestroyWindow("display");
283 Dilatometer_Cleanup();